Cryptogamie, Algologie, 2011, 32 (1): 77-95 © 2011 Adac. Tous droits réservés A checklist of desmids (Conjugatophyceae, Chlorophyta) of Serbia. II. Genus Cosmarium Sanja FUµINATO, Mirko CVIJAN* & Marija STAMENKOVI± Institute of Botany and Botanical Garden „Jevremovac“ Takovska 43, 11000 Belgrade, Serbia (Received 27 May 2010, accepted 7 September 2010) Abstract – The desmid flora of Serbia has been surveyed during various periods. The first data on the distribution of desmids in Serbia date back to 1883 and from then on until 2009 altogether 630 different taxa were identified. Among 23 genera of desmids in all, the most diverse and most commonly found is Cosmarium (242 taxa or 38.4% of the total number of taxa). Taxa belonging to the genus Cosmarium grow in distinctly diverse habitats, from lowland rivers to high-mountain peat bogs. The present paper gives a survey of the major taxonomic and ecological characteristics of the Cosmarium taxa which have been identified in Serbia. The present studies regarding the distribution of Cosmarium taxa over the territory of Serbia, show that extremely rare, very rare and rare taxa comprise 96.3% of all recorded Cosmarium taxa. The species Cosmarium botrytis, C. laeve, C. meneghinii and C. subprotumidum appear widely distributed in the territory of Serbia. High-mountain peat bogs are characterized by the greatest diversity of the Cosmarium taxa. Checklist / desmids / Cosmarium / diversity / floristics / ecology / Serbia Résumé – Checklist des desmidiées (Conjugatophyceae, Chlorophyta) de Serbie. II. Cosmarium. La flore desmidiale de Serbie a été étudiée durant différentes périodes. Les premières données sur la distribution des desmidiées ont été publiées en 1883. Depuis cette date, et jusqu’en 2009, 630 taxons de desmidiées ont été identifiés. Sur un total de 23 genres de desmidiées le genre dominant est Cosmarium (242 taxons, soit 38,4 % du total). En Serbie, les espèces du genre Cosmarium sont observées dans des habitats très diversifiés, depuis les rivières de plaine jusqu'aux tourbières de haute montagne. Cet article donne une vue d’ensemble des caractéristiques taxonomiques et écologiques majeures des taxons du genre Cosmarium identifiés en Serbie. Les espèces extrêmement rares, très rares, et rares, représentent 96,3 % des taxons de Cosmarium. Les espèces à large distribution sur le territoire de Serbie sont Cosmarium botrytis, C. laeve, C. meneghinii and C. subprotu- midum. La plus forte diversité de Cosmarium se trouve dans les tourbières de haute montagne. Liste floristique / desmidiées / Cosmarium / diversité / floristique / écologie / Serbie * Correspondence and reprints: [email protected] Communicating editor: Pierre Compère 78 S. Fužinato, M. Cvijan & M. Stamenkovi† INTRODUCTION The first data on the distribution of taxa belonging to the genus Cosmarium in Serbia were published by Schaarschmidt (1883). He recorded the species Cosmarium margaritiferum, C. turpinii, C. crenatum and C. meneghinii. In the first decade of the 20th Century, Ko≠anin, Kati† and Đorđevi† started more serious studies concerning the diversity and distribution of desmids in Serbia (Ko≠anin, 1908a, 1908b; 1910; Kati†, 1910; Đorđevi†, 1910). Milovanovi† (Milovanovi†, 1959, 1960a, 1960b, 1960c, 1962) greatly contributed to the know- ledge of the desmid flora in Serbia by studying desmid algae of the Vlasina peat bog and Dai†ko lake and the peat bogs on Mts. Kopaonik, µeljin and Ostrozub. Floristically, peat bogs constitute a separate group of wetland habitats that are ecologically clearly distinct from other fresh-water habitats. They are distinguished by particular physico-chemical characteristics as well as by a distinc- tive flora and fauna. Phylogenetically, peat bogs are very important as significant relict habitats. In Serbia they are not as numerous as in northern and western Europe. In adition, they gradually disappear due to the expansion of agricultural areas, deforestation and creation of reservoirs. These factors mutually affect the composition of the total algal flora, including the desmid flora. The most expres- sive example of human influence on peat bogs in Serbia was the formation of a reservoir (called Vlasina Lake) after the Vlasina peat bog had been inundated. Ko≠anin (Ko≠anin, 1910b) recorded 79 taxa from 15 genera in the Vlasina peat bog in 1910, whereas during the same year, Đorđevi† (Đorđevi†, 1910) recorded 193 taxa from 16 genera. The study performed in 1948 (Milovanovi†, 1960a) revealed 217 desmid taxa in all, of which only 39 taxa had been previously recorded by Ko≠anin and Đorđevi† (Ko≠anin, 1910b; Đorđevi†, 1910) and the genus Cosmarium was dominant. In the period of Vlasina Lake formation (1949- 1954) almost the entire community of desmids disappeared (Milovanovi†, 1973). Only a small portion of the community survived in the littoral zone which was not submerged. The main reason of the degradation of the desmid community was explained by sudden changes in physico-chemical water properties. The last exten- sive study of the desmid flora in the Vlasina Lake showed that the diversity of desmids had increased remarkably (Cvijan & Lau≠evi†, 1991b). Up to the present, the total number of known desmid taxa in Serbia amounts to 630, revealing the families Desmidiaceae and Closteriaceae as qualitatively dominant. The cosmopolitan genus Cosmarium, comprising 242 taxa, represents the most diverse genus among desmids. The greatest diversity of the representatives of this genus was recorded in dystrophic ecosystems – high- mountain peat bogs, pits, mires, etc. However, representatives of this genus can also be found in the other types of water bodies and slow running rivers, thus constituting an important part of the phytoplankton and phytobenthic community. In the present paper a survey on the diversity of Cosmarium taxa hitherto recorded from the territory of Serbia is given. MATERIALS AND METHODS This paper is the continuation of Stamenkovi† et al. (2008), which dealt with the distribution of elongate baculiform desmids within Serbia. For the present enumeration, all available literature sources of desmid taxa (published papers, manuscripts and proceedings) concerning the genus Cosmarium occurring Cosmarium checklist in Serbia 79 in Serbia were examined, including theses dealing with the diversity, distribution and ecology of the genus Cosmarium. In addition to the all previously quoted literature data (Stamenkovi† et al., 2008), in the present paper new literature data on two thermomineral springs (Blaženªi† & Cvijan, 1980; Cvijan, 1986), as well as new unpublished data, with respect to the distribution of taxa of the genus Cosmarium in the peat lake of Peshter plateau (algae were collected in July and September 2008 and May 2009) and three salt marshes (Slatina, Peªena slatina and Rusanda) of the Province of Vojvodina (algae were collected several times during 2003 and 2006) are included. Phytoplankton samples were collected by towing a plankton net (mesh size 25 µm) through the open water. Samples of phytobenthos were collected with a pipette from the surface of the bottom deposits. Sampling of epiphytes was performed by squeezing the submerged parts of plants. Water temperature was measured by a digital thermometer with metal electrode, accuracy being 0.1°C. The physico-chemical analysis of the water was performed in the Institute for Public Health of Serbia “Dr. Milan Jovanovic-Batut” applying standard analytical methods, according to JUS-ISO (APHA, AWWA, WPCF). Taxonomic analyses were carried out using a Reichert Diastar microscope with a Canon Power Shot S40 digital camera. Taxa of the genus Cosmarium were identified with the aid of relevant literature (see References). Based on all the localities surveyed in Serbia, frequencies of desmid taxa are designated here according to the following scale: very rare (VR) – taxa recorded in < 10% of investigated sites; rare (R) – taxa recorded in 10 – 30 % of investigated sites; common (C) – taxa recorded in 30 – 70% of investigated sites; frequent (F) – taxa recorded in 70 – 90% of investigated sites; very frequent (VF) – taxa recorded in > 90% of investigated sites. Exceptionally rare (ER) taxa are those recorded in only one locality in the territory of Serbia. RESULTS AND DISCUSSION Habitats of Cosmarium taxa in Serbia Taxa of the genus Cosmarium are widely distributed in Serbia. Text-fig. 1 in Stamenkovi† et al. (2008) shows the location of the habitats of the different taxa of the elongate baculiform desmid taxa, and of the genus Cosmarium as well. In addition, the locations of the four newly investigated habitats of desmids (peat- bog lake at Peshter plateau and three salt marshes), as well as of two thermomineral springs (in Ni≠ka and Ribarska Spa – literature data), which contain representatives of the genus Cosmarium are presented in Text-Figure 1. in the present paper. Different taxa of the genus Cosmarium have been previously reported from both periphyton and phytoplankton communities in Serbia. Unfortunately, most phycologists in Serbia have provided only a list of Cosmarium taxa without additional remarks and with only few illustrations. Therefore it was not possible to verify older reports and reports of taxa recorded from a single locality. Some physico-chemical characteristics of the previously investigated habitats were presented in Stamenkovi† et al. (2008). Some physico-chemical characteristics of newly investigated habitats (peat lake at the Peshter plateau and three salt marshes) and two thermomineral springs